Tested using nix shell github:sophrosyne97/nix/master
LGTM

• system: "x86_64-linux"
• host os: Linux 5.4.112, NixOS, 20.09.20210430.be58d0f (Nightingale)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.4pre20210326_dd77f71
• nixpkgs: /nix/var/nix/profiles/per-user/root/channels/nixos

I'm not sure I agree with the premise that not specifying a regex is likely an error. nix search <flake> is a convenient way to show all the packages in a flake.

Given how long particular full searches can take a full match should occur from the '--all' flag.

Every search is a full search. The regex just restricts what gets printed.

I'm not sure I agree with the premise that not specifying a regex is likely an error.

Perhaps not likely for someone familiar with the command, but I would say it is likely an error for new users.
I made the mistake #3553 mentions myself when I was first trying out the experimental features for nix and couldn't really tell if the full search was a bug or a feature as it was happening. This flag would save new users time and from confusion in the future.

Although an empty search is quick, it is inconsistent with most common search commands which assume that every search begins as an empty one. This idiosyncrasy can make even those familiar with the command error prone as shown with #4739, which in the long run can make the feature not so quick. I thought that the short flag '-a' might bridge the gap between being convenient and quick while also demanding explicit user intent for a full search. That way we can stop the unpleasant experience of having the terminal lock up and make the command a little more predictable.

Another way would be to do what grep does:

›printf '%s\n' {1..3} | grep
Usage: grep [OPTION]... PATTERNS [FILE]...
Try 'grep --help' for more information.

›printf '%s\n' {1..3} | grep ''
1
2
3

Or print info message to stderr, something like:

›nix search
evaluating packages... (this may take long time)

Also flake version of nix search does not have this problem, right?

@sophrosyne97 can you rebase?

@sophrosyne97 can you rebase?

Rebased and tested.

Can you rebase on master and fix the failing test?

@thufschmitt could you review this?

This PR was discussed in the Nix team meeting today:

• @edolstra, @roberth prefer the math simplicity of current implementation
• @tomberek: probably bigger issue is forgetting to specify the flakeref
• @edolstra: let's close or postpone
• @Ericson2314: It seems what is what is actually bugging people is that control-C is not working well (a separate issue). So they accidentally spam their terminally with a huge list of packages and then cannot easily get out of it. So if we solve that problem (fix C-c, page output) then this won't be so bad.

Decision: close

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/2023-08-11-nix-team-meeting-79/31627/1